Sheet discharging device and image forming apparatus incorporating same

Abstract

A sheet discharging device, which is included in an image forming apparatus, includes a sheet discharging tray, a sheet discharging roller pair, a full state detection feeler pivotably supported and including a center feeler to measure a height of a center part of the recording medium and an edge feeler to measure a height of an edge part of the recording medium, and a full state detection sensor to detect a position of the full state detection feeler. A distance between a leading edge of the center feeler and an upper surface of the sheet discharging tray is smaller than a distance between a leading edge of the edge feeler and the upper surface thereof. The leading edge of the edge feeler is located closer to the upper surface of the sheet discharging tray than a common tangential line of the sheet discharging roller pair.

What is claimed is: 
     
       1. A sheet discharging device comprising:
 a sheet discharging tray to which a recording medium having an image formed thereon is discharged; 
 a sheet discharging roller pair to discharge the recording medium conveyed by a sheet conveying member disposed upstream from the sheet discharging roller pair to the sheet discharging tray; 
 a full state detection feeler pivotably supported to measure a height of a stack of recording media including the recording medium on the sheet discharging tray, 
 the full state detection feeler comprising
 a center feeler to measure a height of a center part of a flat surface of the recording medium in a direction perpendicular to a sheet conveying direction, and 
 an edge feeler to measure a height of an edge part of the flat surface of the recording medium in the direction perpendicular to the sheet conveying direction; and 
 
 a full state detection sensor to detect a position of the full state detection feeler to determine whether the sheet discharging tray is in a full state, 
 wherein a distance between a leading edge of the center feeler and an upper surface of the sheet discharging tray is smaller than a distance between a leading edge of the edge feeler and the upper surface of the sheet discharging tray, 
 wherein the leading edge of the edge feeler is located closer to the upper surface of the sheet discharging tray than a common tangential line of the sheet discharging roller pair. 
 
     
     
       2. The sheet discharging device according to  claim 1 , wherein, due to a contact of the leading edge of the recording medium conveyed by the sheet discharging roller pair with the center feeler, the full state detection feeler is pushed up until a trailing edge of the recording medium passes through the center feeler,
 wherein, while the recording medium is in contact with the center feeler, the recording medium is separated away from the edge feeler. 
 
     
     
       3. The sheet discharging device according to  claim 1 , wherein the center feeler is located at a center of the axial direction of the full state detector feeler,
 wherein the leading edge of the center feeler contacts the recording medium on the sheet discharging tray, 
 wherein the edge feeler includes multiple edge feelers located at both ends of the center feeler, 
 wherein the respective leading edges of the edge feelers continuously disposed in the axial direction of the sheet discharging pair contact the recording medium on the sheet discharging tray. 
 
     
     
       4. The sheet discharging device according to  claim 3 , wherein the full state detection sensor detects the full state of the sheet discharging tray when the leading edges of the edge feelers contact the recording medium on the sheet discharging tray,
 wherein the position of the leading edges of the edge feelers at the full state detection of the sheet discharging tray is located within a range of ±5 degrees with respect to a common tangent line of the sheet discharging roller pair in a cross-sectional view perpendicular to the axial direction of the sheet discharging roller pair. 
 
     
     
       5. The sheet discharging device according to  claim 1 , wherein a range of the edge feelers in the axial direction of the sheet discharging roller pair is set greater than a maximum width of a printable paper width in an image forming apparatus. 
     
     
       6. The sheet discharging device according to  claim 1 , wherein the center feeler and the edge feelers of the full state detection feeler are connected continuously without any slits. 
     
     
       7. The sheet discharging device according to  claim 1 , wherein the full state detection feeler includes a weight container. 
     
     
       8. The sheet discharging device according to  claim 1 , wherein the sheet discharging tray rotates about an axial center thereof,
 wherein a maximum rotational locus of the sheet discharging tray and a maximum rotational locus of the full state detection feeler share an area where the maximum rotational focuses overlap. 
 
     
     
       9. The sheet discharging device according to  claim 8 , wherein, when the full state detection feeler is not in contact with the recording medium, the full state detection feeler rotates along with an aid of gravity and retreats to a position outside a maximum rotational locus of the sheet discharging tray. 
     
     
       10. An image forming apparatus comprising:
 an image forming unit to form an image on a surface of an image carrier; and 
 the sheet discharging device according to  claim 1 .